Apple PC Compatibility Card (Installation) - Manual (Page 39)

2 Remove the rubber block from the large end of the internal PC audio/video assembly.
The rubber block is glued to the top of the connector, but you can peel
it off easily with your fingers. The rubber block must be removed for
this installation.
3 Plug the large end of the internal PC audio/video connector into the socket on the
computer’s main logic board, and fold the cable near the connector as shown in the
illustration below.
Pinch the fold in the cable so that the cable lies flat.
(Side view)
The ribbon cable should extend from the bottom of the connector as shown
here. If the ribbon cable extends from the top of the connector, unplug
the cable from the small card, and plug the connector on the
other end of the ribbon cable into the small card.
Fold the ribbon cable as shown here.
Small card Ribbon cable
Small card Connector
Connectors
Peel off the rubber block with your fingers.
39 Installing the PC Compatibility Card in a 6400 Series Macintosh Computer